The engineering plastics are excellent in mechanical characteristics, heat resistance and molding processability, and their utilization are expanding in the fields of automobile parts, machinery parts and electric/electronic parts.
In the electric/electronic field, since a safety in use, a production efficiency and the utilization of recycled resources are required, while a process of making the parts thereof as having a light weight, thin thickness, short length and small size, and also having a high performance is progressing, the engineering plastics, particularly the aromatic polyester as a central figure, which is excellent in heat resistance, molding processability and chemical resistance and relatively easy for making it of flame retardant, are extending their range of uses.
As to the method for making the engineering plastics of flame retardant, a technology for blending a red phosphorus and a zinc compound such as zinc borate, etc., with a polyamide was disclosed in the Japanese unexamined patent publication 6-145504. Although the polyamide itself has an excellent tracking resistance, the changes in electrical and mechanical characteristics caused by the absorption of moisture are large. And it is known that the flame retardant property of the polyamide is increased by an interaction between phosphorus atom and nitrogen atom in the polymer skeleton of the polyamide. Therefore the technologies for aiming at the method for making the polyamide of flame retardant are known besides the above Japanese unexamined patent publication 6-145504.
On the other hand, the aromatic polyester is widely used as the electric/electronic parts. In this case, it is made of flame retardant by blending an organic halogenous compound therewith in most of the cases for increasing the safety for a fire of the product composed of the molded product thereof.